The study, which was presented on Sunday, is based on data from 2,000 people where the average age was 31 years.
It showed that the vaccine provided little or no protection in people who may experience mild or moderate symptoms of the mutation.
Whether the vaccine protects against severe or life-threatening symptoms is not clear because those who participated in the study did not belong to any risk group.
No plan to stop the vaccine in Sweden
According to Anders Tegnell, however, there is currently no plan to stop Astra Zeneca's vaccine in Sweden.
- The South African mutation has not proven to be as good at spreading as the British one.
But it is a warning sign that you definitely need to take with you in the continued vaccine development, says state epidemiologist Anders Tegnell to SVT Vetenskap.
South Africa has chosen to pause its vaccination after the new study.
The country's health minister Zweli Mkhize announced on Sunday that they are awaiting comments from more researchers to know how to proceed, according to Reuters.
The study awaits scientific review
The study from the University of the Witwatersrand in Johannesburg has not yet been scientifically reviewed.
If it proves necessary, Astra Zeneca will develop a second vaccine that also protects better against other virus mutations.
- A preparedness is needed that follows the development of the virus to develop vaccines that work on all types of mutations, says Anders Tegnell.